Suturing continues to be the primary method of closure for most surgical wounds. Security of these closures historically has been highly dependent on the technique of suture placement and the ability of the surgeon to tie secure knots.1–4 Knotless sutures (so-called barbed sutures) have protruding spurs along the surface of monofilament suture. These spurs or barbs allow the suture to pass through tissue in 1 direction without undue friction, but they catch or anchor the suture within the tissue with each passage to prevent loosening, thus eliminating the need for a terminal knot.5–8
Use of barbed suture can reduce surgical time and provide for more even distribution of tension along wound edges, which purportedly reduces tissue ischemia. Barbed suture maintains apposition of tissue more consistently than does smooth suture, and because of the absence of a bulky terminal knot, healing occurs with less foreign body response and less scarring. This reportedly has resulted in improved cosmetic outcomes, less suture extrusion, and improved tissue healing.5,6,9–11,a
Because of these advantages, barbed suture has been gaining favor over smooth suture for a variety of procedures in both human and veterinary surgery. Barbed sutures have been used in humans; those uses include intradermal closures, orthopedics (arthrotomy or tendon repair), gastrointestinal surgery, obstetric and gynecologic procedures, urologic procedures, and plastic surgery (body contouring, breast lifts or reductions, or abdominoplasties).9,12–19 In the veterinary field, barbed suture has been described for use in intradermal closures, gastrointestinal tract surgery (gastropexy, gastrotomy or enterotomy, or resection and anastomosis), orthopedics (arthrotomy or tendon repair), cystopexies, diaphragmatic herniorrhaphies, internal inguinal ring closures, and cesarean sections.20–32
A knot is the most common site of stitch or suture line failure because of a decrease in tensile strength of conventional smooth suture incorporated within the knot.1,33 Barbed suture has been developed to eliminate the need for a knot during wound closure. Instead, additional needle passes through tissue at the end of the continuous suture line (termed an end-pass configuration in the study reported here) can be used to terminate the closure. Security of continuous barbed suture lines depends on tissue engagement of the barbs throughout the line,34 but it could also depend on the end-pass configuration or terminal anchor of the suture line. However, the authors are aware of no studies in human or veterinary surgery that have been conducted to examine the security of continuous barbed suture lines terminated with an end-pass technique or without an end-pass anchor.
The objectives of the study reported here were to compare mechanical properties, mode of failure, and end point tensile strength of 3 end-pass techniques commonly used in human plastic surgery and veterinary medicine to terminate barbed suture closures in the skin of canine cadavers and also to compare results for those 3 end-pass techniques with results for a control group that did not have an end-pass configuration. We hypothesized that the mechanical properties, mode of failure, and end point tensile strength would not differ among the 3 end-pass configurations. We also hypothesized that these variables for each of the 3 end-pass techniques would differ from results when no end-pass technique was used.
Materials and Methods
Sample
Cadavers of 4 healthy middle-aged Beagles with no obvious skin abnormalities were originally included in the study. After initial testing was conducted, it was decided to include cadavers of 2 additional healthy middle-aged Beagles. All dogs were euthanized by IV administration of pentobarbital as part of an unrelated study.b Cadavers were stored at 5°C and used within 48 hours after the dogs were euthanized. Approval by an institutional animal care and use committee was not obtained because the dogs were euthanized for purposes unrelated to this study and the cadavers were used secondarily.
Skin incisions and intradermal closure
Full-thickness, 4-cm-long, parasagittal wounds were created through the skin and tissues superficial to the deep fascia of cadavers; incisions were located 5 cm lateral to the dorsal midline (Figure 1). Wounds (30 incisions in the initial 4 cadavers and 10 incisions in the 2 additional cadavers) were created on both sides of the cadavers. Each wound was closed by use of a new package of unidirectional 3-0 barbed suturec on a 3/8 circle precision reverse-cutting 19-mm needle with 30-cm barb configuration inserted in a continuous intradermal pattern. The investigator who performed the intradermal closure (PJR) was careful to avoid weakening the suture by ensuring that the strand was not kinked and was not grasped with instruments. Closures were performed consistently throughout the study. Suturing commenced from the right end of the incision and proceeded along the incision to the left. Each continuous suture line was initiated by passing the suture deep to superficial through the dermis on the near side and superficial to deep on the opposite side at a point 0.5 cm from the start of the incision. Next, a suture anchor loop formed by passing the needle through the unidirectional strand loop was buried deep in the subcutaneous tissues at a point approximately 0.5 cm from the start of the incision. This was achieved by inserting the next needle passage from deep to superficial below the locked loop, with the needle exiting at the beginning of the incision within the dermis (Figure 2). Four passages, each 0.5 cm long and at 0.2 cm deep to the epidermis, were placed within the dermal layer on each side of the incision in a continuous pattern oriented parallel to the skin surface. Each suture terminated with 1 of 3 end-pass configurations or without an end-pass configuration (control group).
Photographs of three 4-cm-long wounds on the dorsolateral aspect of a canine cadaver (A), the continuous pattern of closure within the dermal layer (B), and the wounds at completion of closure with barbed suture (C). In panels A and C, notice that the wounds are centered in a 6 × 8-cm piece of skin and subcuticular tissue that was subsequently undermined and removed for biomechanical testing. The direction of the suture line is indicated for each wound (arrow). The skin samples were identified with a randomized code (1AeR, 2BeR, and 3CeR).
Citation: American Journal of Veterinary Research 77, 12; 10.2460/ajvr.77.12.1392
Illustrations of the initial loop (1) and end-pass A (2), end-pass B (3), and end-pass C (4) techniques for intradermal closure with unidirectional barbed suture. End-pass A was a 1-pass technique that began at the terminal end of the incision with the needle passed into the subcutaneous tissue and exiting 1 cm perpendicular or 90° from the axis of the incision on the same side as the last intradermal passage. End-pass B was a 2-pass technique that began at the terminal end of the incision with the needle passed into the subcutaneous tissue and exiting the skin 1 cm parallel to the incision, which was followed by a second passage that involved passing the needle into the subcutaneous tissue immediately adjacent to the exit site and back the opposite direction to exit at the end of the incision. End-pass C was another 2-pass technique that began at the terminal end of the incision with the needle inserted into the subcutaneous tissue exiting between the skin edges at 1 cm from the end of the incision, which was followed by a second passage back into the subcutaneous tissue perpendicular to the incision axis to exit 1 cm from the end of the incision on the same side of the incision as the last intradermal passage. (Image provided by KTB Studios LLC; published with permission).
Citation: American Journal of Veterinary Research 77, 12; 10.2460/ajvr.77.12.1392
Each wound was labeled by use of a nonrepeating random number scheme, with the caveat that wounds on a specific dog were allocated to each treatment group before additional wounds were assigned for a second time to one of the treatment groups. Three end-pass configurations were used. A 1-pass technique (end-pass A) began at the end of the incision with the needle passed into the subcutaneous tissue and exiting 1 cm perpendicular or 90° from the axis of the incision line on the same side as the last intradermal passage (Figure 2). A 2-pass technique (end-pass B) began at the end of the incision with the needle passed into the subcutaneous tissue and exiting the skin 1 cm parallel to the incision line, which was followed by a second passage that involved passing the needle into the subcutaneous tissue immediately adjacent to the exit site and back the opposite direction to exit at the end of the incision line. Another 2-pass technique (end-pass C) began at the end of the incision with the needle inserted into the subcutaneous tissue and exiting between the skin edges at 1 cm from the end of the incision, which was followed by a second passage back into the subcutaneous tissue perpendicular to the incision line axis and exiting 1 cm from the end of the incision on the same side of the incision as the last intradermal passage. All suture strands were cut flush with the skin surface (ie, dense connective tissue) to complete the end-pass technique.
No end-pass technique was used for the fourth group (control group). Instead, after the final passage was inserted in the dermal layer near the end of the incision, the barbed suture was cut to leave approximately 2 mm of suture exposed after it exited the skin.
All suturing was performed by 1 investigator (PJR), who was a resident in a veterinary surgery training program. There was an equal number of each end-pass configuration and the control configuration (n = 10).
Sample collection for testing
After wound closure was completed, each wound was excised. Each excised sample (6 × 8-cm rectangular sample centered on the suture line, with 1 cm of intact [nonincised] skin on each end of the 4-cm-long incision) was composed of skin and subcutaneous tissues (Figure 1). A No. 10 scalpel blade was used to sharply undermine each skin sample deep to the subcutis to create a full-thickness skin sample. The incision line extended through the subcutis of each sample. The wound closures were coded; thus, investigators were not aware of the source of the excised samples. Constructs were arbitrarily assigned with regard to location site on the cadaver and end-pass configuration. Coded constructs were biomechanically tested within 6 hours after incision closure.
Mechanical testing
A servohydraulic testing machined was used to obtain data on tensile load and actuator position. The machine consisted of squeeze-grip clamps,e which were lined with wire mesh to prevent tissue slippage; clamps were located on the base of the servohydraulic machine and the load cell. Each sample was manually secured in the load fixture in a manner that allowed application of a tensile load in a plane perpendicular to the long axis of the suture line (Figure 3). A 5,000-N load cell was used; the cell was verified to have accuracy of 0.5% down to 0.01% of maximum capacity. Tensile load was applied quasistatically under displacement control at a rate of 100 mm/min until construct failure. Load and displacement data were collected at 100 Hz. Prior to ramp-to-failure testing, samples were cyclically preconditioned (0 to 50 N for 10 cycles).
Photograph of a representative skin sample from a dog with an incision closed in an intradermal pattern with unidirectional barbed suture (sample Control 4AFL). The sample has been loaded into squeeze-grip clamps located at the base of a servohydraulic machine for mechanical testing. No end-pass technique was used for this sample. Instead, after the final suture passage was inserted in the dermal layer near the terminal end of the incision, the barbed suture was cut to leave approximately 2 mm of suture exposed after it exited the skin. Notice the failure of wound closure, which is evident as a gap > 1 cm along the continuous intradermal suture line. Scale on the far left side is in centimeters.
Citation: American Journal of Veterinary Research 77, 12; 10.2460/ajvr.77.12.1392
Samples were tested in a randomized nonrepeating manner whereby investigators were unaware of the end-pass configuration group; however, the investigators were aware of the samples for the control group. All ramp-to-failure tests were videotaped to determine mode of failure. The mode of failure or cause of failure of wound closure was recorded for 3 categories (suture rupture, suture slippage at termination (ie, terminal end of the suture line), and tissue rupture [ie, suture pull-out from the tissue]) or a combination of those categories. Failure of wound closure was defined as a gap (> 1 cm) of the wound closure along the continuous intradermal suture line.
Collected data were used to generate a load-displacement curve for each sample (Figure 4). Displacement was the distance and direction the suture stretched between a starting and stopping position at failure. Stiffness (the extent to which a construct resisted deformation in response to applied force) and maximum (failure) load were calculated. Stiffness was calculated as the slope of the force-displacement curve in the linear region prior to yielding or failure of a sample. Maximum load (peak load at failure, which was the force required for the suture-skin construct to fail) was determined as the load of greatest magnitude located along the curve. Additionally, failure displacement was determined at the maximum load.
A representative load-displacement curve generated during ramp-to-failure testing of a skin sample with an incision closed in an intradermal pattern with unidirectional barbed suture. Notice the peak load (asterisk). Stiffness was calculated in the same region (ie, 30 to 50 N [red portion of line]) for each sample because all samples contained this region.
Citation: American Journal of Veterinary Research 77, 12; 10.2460/ajvr.77.12.1392
An additional evaluation was performed. The load-displacement curve for each sample, sample examination postmechanical testing, and video recordings were further evaluated to determine the load at the first slip of the end-pass configuration (or loosening of the suture for the control configuration), regardless of whether the slip ultimately caused failure of the wound closure.
Statistical analysis
Distribution of the data was determined by use of a Shapiro-Wilk normality test. A Brown-Forsythe test was also used to determine whether the data had equal variance. All data sets were normally distributed and had equal variance. A 1-way ANOVA with a Tukey post hoc test was performed with statistical softwaref to determine significant differences. Descriptive statistics (ie, mean, SD, and frequency for each failure mode) were used to describe the distribution of observed values of the mechanical forces (ie, peak load, displacement, and stiffness) measured and the proportion of end-pass slippage according to distribution of the data. Mean and SD were calculated for each treatment group and for each specific outcome variable. Categorical data (ie, mode of failure and end-pass slippage) were compared descriptively. Significance was set at values of P ≤ 0.05 for all analyses.
Results
Mode of failure
A total of 38 wound constructs were tested, 28 of which had an end-pass configuration. One wound closure (end-pass A) was excluded because the barbed suture was cut during harvesting of the sample prior to mechanical testing. Another wound closure (end-pass B) was excluded because the investigator noticed that for the second passage of the end-pass configuration, the barbs did not effectively engage the tissues because the second passage of the needle appeared to enter the hole created by the first passage of the needle; the data for this wound closure were excluded because if this had been noticed in a clinical setting, the situation would have been rectified by placing another passage of the suture to serve as an anchor.
Of the 28 wounds with an end-pass configuration that were tested, 23 (82.1%) had failure of wound closure attributed to suture rupture outside the beginning and end regions of the continuous suture lines. Of the 38 wounds that were tested, 24 (63.2%) had failure of wound closure attributed to suture rupture. Tissue rupture, which did not involve the suture or end-pass configuration, was not observed in any of the 38 samples.
Suture slippage at the end of the suture line or failure of the barbed suture end-pass configuration to adequately engage the tissues and anchor the continuous suture line was another mode of failure. Of the 9 constructs for end-pass A, 3 had failure of the wound closure attributable to suture slippage. Of the 9 constructs for end-pass B, 0 had failure of the wound closure attributable to suture slippage. Of the 10 constructs for end-pass C, 2 had failure of wound closure attributable to suture slippage. Of the 10 control constructs, 9 had failure of wound closure attributable to suture slippage (Figure 5).
Bar graphs of the number of constructs with suture slippage, regardless of whether the slippage ultimately caused failure of wound closure (black bars), and the number of constructs with suture slippage that ultimately caused failure of wound closure (gray bars) for 4 groups of barbed suture constructs in the skin of canine cadavers.
Citation: American Journal of Veterinary Research 77, 12; 10.2460/ajvr.77.12.1392
Forces
Peak load at failure, displacement at failure, and stiffness were compared among the 4 groups (Table 1). There were no significant differences among the 4 groups for peak load to failure, failure displacement, and stiffness, except for a significant difference for displacement between end-pass B and the control configuration (Table 2).
Mean ± SD values for peak load at failure, displacement at failure, and stiffness for skin incisions of canine cadavers that were sutured with 3 end-pass configurations or without an end-pass configuration (control group).*
| Treatment group | Peak load (N) | Displacement (mm) | Stiffness (N/mm) |
|---|---|---|---|
| End-pass A (n = 9) | 96.51 ± 74.09 | 16.71 ± 2.76 | 7.28 ± 2.09 |
| End-pass B (n = 9) | 123.66 ± 29.09 | 18.41 ± 3.93 | 8.87 ± 1.06 |
| End-pass C (n = 10) | 95.28 ± 45.90 | 17.16 ± 3.34 | 7.81 ± 2.19 |
| Control (n = 10) | 83.72 ± 40.25 | 13.61 ± 3.49 | 9.37 ± 2.63 |
End-pass A was a 1-pass technique that began at the terminal end of the incision with the needle passed into the subcutaneous tissue and existing 1 cm perpendicular or 90° from the axis of the incision on the same side as the last intradermal passage. End-pass B was a 2-pass technique that began at the terminal end of the incision with the needle passed into the subcutaneous tissue existing the skin 1 cm parallel to the incision, which was followed by a second passage that involved passing the needle into the subcutaneous tissue immediately adjacent to the exit site and back the opposite direction to exit at the end of the incision. End-pass C was another 2-pass technique that began at the terminal end of the incision with the needle inserted into the subcutaneous tissue and existing between the skin edges at 1 cm from the end of the incision, which was followed by a second passage back into the subcutaneous tissue perpendicular to the incision axis to exit 1 cm from the end of the incision on the same side of the incision as the last intradermal passage. For the control group, no end-pass technique was used. Instead, after the final passage was inserted in the dermal layer near the terminal end of the incision, the barbed suture was cut to leave approximately 2 mm of suture exposed after it exited the skin.
P values for comparison of peak load at failure, displacement at failure, and stiffness among groups with 3 end-pass configurations or without an end-pass configuration (control group).*
| Group comparison | Peak load | Displacement | Stiffness |
|---|---|---|---|
| End-pass A vs end-pass B | 0.66 | 0.72 | 0.39 |
| End-pass A vs end-pass C | 0.94 | 0.99 | 0.15 |
| End-pass B vs end-pass C | 0.32 | 0.85 | 0.95 |
| End-pass A vs control | 1.00 | 0.22 | 0.95 |
| End-pass B vs control | 0.61 | 0.02 | 0.69 |
| End-pass C vs control | 0.95 | 0.11 | 0.35 |
Values were considered significant at P ≤ 0.05.
See Table 1 for remainder of key.
Suture slippage at the terminal end of the suture line
Suture slippage at the terminal end of the suture line was evaluated for each of the 38 samples, regardless of whether the slippage ultimately caused failure of wound closure. End-pass A had suture slippage in 5 of 9 samples, and 3 of these 5 end-pass slips caused failure of wound closure (Figure 5). End-pass B had suture slippage in 3 of 9 samples, but none of these 3 end-pass slips caused failure of wound closure. End-pass C had suture slippage in 4 of 10 samples, and 2 of these 4 end-pass slips caused failure of wound closure. The control configuration had suture slippage in 10 of 10 samples, and 9 of these 10 slips caused failure of wound closure. All remaining suture slips occurred prior to failure of wound closure, and all of those failures were attributable to suture breakage.
Load at first suture slippage at termination was compared among the 4 groups. There was not a significant (P = 0.60 to 1.00) difference in mean ± SD load among the 4 groups (end-pass A [n = 9], 66.78 ± 30.29 N; end-pass B [9], 86.69 ± 47.27 N; end-pass C [10], 84.50 ± 21.88 N; and control configuration [10], 61.80 ± 28.56 N).
Discussion
For smooth suture, a knot is considered the most important part of the suture loop and is ultimately the weakest part, decreasing breaking strength of the untied suture by as much as 35% to 95%.1 Failure of a knot may lead to dehiscence of an incision, which could be devastating in a clinical setting.35 Barbed suture has been used in human and veterinary surgery because it eliminates the need for knots and provides a number of other purported advantages. To determine the end-pass configuration that offered the most security against wound disruption under tension forces, the study reported here was conducted to compare mode of failure and mechanical forces (peak load, displacement, and stiffness) among 3 configurations (end-pass A, end-pass B, and end-pass C) and a control configuration. We also evaluated load at first slip of the end-pass configuration (or loosening of the end of the suture line for the control configuration), regardless of whether the slip ultimately caused failure of the wound closure. This helped the investigators determine the strength and security for each end-pass technique and its ability to maintain a secure closure even after initial suture slippage.
Extrusion, infection, and palpability have all been reported as uncommon complications of barbed sutures, which are similar to complications reported for smooth sutures.36,37 Investigators of a recent study32 reported that barbed suture devices are a safe and efficacious alternative for cosmetic skin closures in porcine skin. Authors of that study32 found yield strengths of wound closures were comparable to those for closures performed with conventional absorbable monofilament suture secured with knots; however, the authors did not compare wound closure strength for barbed sutures versus smooth monofilament sutures. In the study reported here, the edges of skin samples were purposefully kept intact, which allowed for placement of an end-pass configuration. We believed this was a more clinically applicable technique, in contrast to the constructs used in the aforementioned study,32 which did not have intact skin at both ends of the intradermal suture line.
Purported advantages of barbed suture include less foreign-body reaction, reduction in surgical time, improved tissue apposition, even distribution of tension along the incision, better wound healing as a result of a reduction in ischemia, less suture extrusion, and improved cosmetic outcomes.5,6,9–11,a Investigators of a recent study12 found that for human body contouring, wound closure with standard absorbable suture in a continuous pattern resulted in a greater incidence of complications (infections, wound problems, and seromas) than did closures achieved by use of barbed suture. In another study,38 investigators evaluated intradermal closure in an in vivo study of pigs, and they noticed no evidence of suture extrusion or tissue distortion and no major wound complications throughout the duration of the study. However, authors of these studies12,38 did not discuss breakdown of the wounds over time. Barbed suture has many potential advantages for intradermal closure in dogs, but most of the available literature about use of barbed suture for skin closure is for studies on humans or pigs. Knotless closures may decrease the potential for knot-related complications (eg, extrusion, pain, inflammation, or visibility),1,10,39 but the authors are not aware of any peer-reviewed literature in which end-pass configurations were compared to barbed suture without such a configuration or whether an end-pass configuration is even necessary to secure the suture line for barbed sutures.
Biomechanical strength of barbed suture is a function of barb geometry, cut angle of the barbs, depth of the barbs, total number of barbs, and helicity.6,32,40,g The strength of barbed sutures is attributable to the suture's ability to resist retrograde movement as a result of the anchoring effect of the barbs in the tissue.5,6 In continuous suture lines, smooth monofilament sutures have a tendency to slide toward the middle of the incision, where the tension is the greatest; this causes additional tissue stress and may lead to suture pull-through.5,6 Security of barbed sutures relies on the ability of the barbs to precisely grasp the tissue at multiple points and allow for uniform distribution of tension and tissue-holding forces across a wound.10 Use of barbed suture for wound closure provides secure tissue approximation while also requiring less suture material than for conventional closures with smooth suture.14
Cutting barbs into a monofilament suture decreases the effective diameter of the suture and results in suture strength that is similar to that for a smooth monofilament suture 1 size smaller.32 It is important to mention that there are 2 commercially available barbed sutures,c,h which differ with regard to barb geometry, barb spacing, and size. These 2 barbed suture types were not compared in the present study, but their differences may affect tissue engagement and, ultimately, mechanical security of a closure. The barbed sutureh that was not evaluated in the study reported here has been labeled as 1 size smaller than the suture into which the barbs are cut. This is in comparison with the barbed suturec that was used in the present study, which has been labeled as the size of the original monofilament used to create the barbed suture. Thus, the reason that we used 3-0 barbed suturec was because it had strength similar to that of 4-0 smooth monofilament suture of the same type, which is commonly used and the preferred suture size for intradermal wound closures in veterinary medicine.41
Security of a continuous intradermal suture line relies on the tissue anchor points of the barbs but likely also relies on the end-pass configuration. A barbed suture holds better when each barb snares collagen fibers; therefore, a sinuous passage is preferable to a straight passage because more collagen is encountered. If a suture begins to pull out, new fibers are then pressed against the barbs.6 For the present study, choice of end-pass configurations was based on techniques commonly used in humans, primarily plastic surgery. Techniques include a backstitch (J-loop), a single passage 1 to 2 cm from the end of the wound, and a double-passage end-pass configuration.5,12,14,42
The methods used in the study reported here were similar to those of a 2004 study4 and those of a 2014 study43 in which investigators evaluated monofilament suture and knots in intradermal wound closures in skin of canine cadavers. The cadavers were fresh (dogs had been recently euthanized), and the suture material was pulled through fat when the continuous intradermal closure and end-pass techniques were performed, which takes into account influence of fat and body fluid on knot security. In the present study, we found that end-pass A and B were subjectively easiest to perform. For end-pass C, the suture looped back through the incision, and extra care was necessary when passing the needle to ensure that it did not disrupt the adjacent continuous suture line.
Maximum load, displacement, and stiffness were calculated at failure of wound closure and recorded from a load-displacement curve generated for each sample by application of linear forces. There was no significant difference among the 3 end-pass techniques for displacement, maximum load, peak load, or stiffness. However, there was a significant difference for displacement at failure of wound closure between end-pass B and the control configuration, with a higher displacement recorded for end-pass B. This likely would not have any clinical importance, and it was attributed to the fact that most of the failures of wound closure for the control configuration were attributable to early suture slippage at the end of the suture line, which occurred with less displacement at ultimate failure of wound closure. This was in comparison with end-pass B, whereby all failures of wound closure were attributable to suture rupture, which allowed greater stretching of the construct and displacement before ultimate failure of wound closure. There was also no significant difference between the 3 end-pass techniques and the control configuration when comparing load at first slip of the end-pass configuration or end of the suture line.
To determine whether an end-pass configuration was necessary to secure an intradermal suture, a control group without an end-pass configuration was compared with the end-pass groups. In the control group, the suture line relied completely on the barbs adequately engaging tissue throughout the intradermal suture line. The control group did not have the added security of an end-pass configuration engaging intact tissue at the end of the suture line, which may further lead to slippage of the continuous intradermal suture line throughout the incision and ultimately lead to failure of wound closure. This observation was supported by results of the present study because 9 of 10 slips at the end of the intradermal suture line for the control group caused failure of wound closure. Therefore, an end-pass technique would be important to protect continuous intradermal suture lines from wound disruption attributable to slippage at the end of the suture line. For situations in which no end-pass configuration is used, if the tensile force placed on the construct does not break the suture, then the end of the continuous suture line would be expected to slip first because it has no anchor and only a few barbs engaging the dermis. The rest of the suture line has barbs engaged in tissue in successive passages of suture that keep the remaining suture line from slipping.
End-pass A, which consisted of a single passage of suture, could be quickly and easily performed and required that less suture material be buried in the tissues. Because this end-pass configuration consisted of only a single passage that engaged the skin, it may have resulted in suture slippage that could ultimately have led to wound failure (6 of 10 end-pass A configurations had suture slippage that caused failure of wound closure).
An advantage of end-pass B was that it engaged dense connective tissue (ie, skin) twice, with the double passage potentially creating a more secure anchor. This was supported by the fact that none of the 9 end-pass B configurations had suture slippage that ultimately caused failure of wound closure. A disadvantage of this end-pass technique may include the fact that when performing the second passage, the needle may be directed into the same hole created by the first passage, which may disturb barbs on the suture and result in inadequate purchase of the tissues by the barbs. This situation occurred for the end-pass B construct that was excluded from the study. Other potential disadvantages of this end-pass technique include an increase in the amount of time required to complete the 2 needle passages, which in the investigators' opinion was minimal, and an increase in the amount of suture or foreign material incorporated in the double-pass configuration.
End-pass C was also a double-pass configuration that potentially created a more secure anchor. The difference between end-pass B and C was that end-pass B engaged intact dense connective tissue with both passages, whereas end-pass C engaged only loose subcutaneous tissue with the first passage but dense connective tissue with the second passage. Two of 4 suture slips for end-pass C ultimately caused failure of wound closure. In the investigators' experience, it was more technically challenging to perform end-pass C because the first passage was a reverse passage back through the incision that was deep to the intradermal suture loops, and care was used to avoid damaging the intradermal suture line by piercing or scoring with the needle, which may have caused weakening of the intradermal suture line or could even have severed the suture. Similar to the situation for end-pass B, end-pass C required an increase in the amount of time needed to complete the configuration and an increase in the amount of suture material incorporated in the configuration.
Limitations of the present study included subtle variations in suturing technique, which included size of the space between successive passages, subjective amount of force used to apply tension to the continuous suture line, and variability in the amount of suture tension on the suture line, despite the fact 1 investigator performed all wound closures and the investigator applied tension to the suture in the manner that would have been used for wound closure in a clinical situation. Also, the continuous suture line was inserted in canine cadavers, as opposed to live dogs with viable tissue. Another limitation of the study reported here was that the suture constructs were loaded only to failure and did not undergo cyclic loading, which would have been more clinically relevant. There also were a limited number of samples for each end-pass configuration. Furthermore, we used a 3-0 barbed suturec for end-pass testing. It is important to mention that authors of another study32 found that the primary mode of failure was barb slippage (79% of the failures) with the same barbed suture,c compared with results for another barbed sutureh (33% of the failures). Therefore, results of the present study may not apply to that other barbed suture,h which was not tested in the study reported here. Future studies should include a larger sample size, live animals, and cyclic loading of suture constructs.
In the study reported here, an end-pass configuration was important to limit disruption of wound closure as a result of suture slippage. All intradermal suture lines with an end-pass configuration had fewer failures of wound closure attributable to suture slippage at the termination point. Each of the 3 end-pass configurations initially had suture slippage and ultimately failed at loads that were not significantly different among the configurations; thus, all 3 end-pass configurations may be considered when a continuous intradermal suture line is used in a clinical setting. All 3 end-pass configurations may be used as the final end-pass anchor at the end of a continuous intradermal suture line; however, the authors advocate the use of end-pass B as a reliable final end-pass configuration because none of the end-pass suture slippages for that configuration ultimately caused failure of wound closure.
Acknowledgments
Supported in part by Surgical Specialties Corporation.
Footnotes
Rodeheaver GT, Pineros-Fernandez A, Salopek LS, et al. Barbed sutures for wound closure: in vivo wound security, tissue compatibility and cosmesis measurements (oral presentation). 30th Annu Meet Soc Biomater, Memphis, April 2005.
Pre-Clinical Research Services Inc, Fort Collins, Colo.
Quill Monoderm (VLM-2003V), Surgical Specialties Corp, Wyomissing, Pa.
MTS Systems Corp, Eden Prairie, Minn.
Vice-Grip, Irwin, Huntersville, NC.
R, version 3.2.2, R Foundation for Statistical Computing, Vienna, Austria. Available at: www.r-project.org/. Accessed Mar 11, 2015.
Leung JC, Ruff GL, Batchelor SD. Performance enhancement of a knotless suture via barb geometry modifications (abstr), in Proceedings. 7th World Biomater Cong 2004;1587.
V-Loc 90 wound closure device, Medtronic, Minneapolis, Minn.
References
1. Trimbos JB. Security of various knots commonly used in surgical practice. Obstet Gynecol 1984; 64: 274–280.
2. Shaw AD, Duthie GS. A simple assessment of surgical sutures and knots. J R Coll Surg Edinb 1995; 40: 388–391.
3. Marturello DM, McFadden MS, Bennett A, et al. Knot security and tensile strength of suture materials. Vet Surg 2014; 43: 73–79.
4. Richey ML, Roe SC. Assessment of knot security in continuous intradermal wound closures. J Surg Res 2005; 123: 284–288.
5. Paul MD. Bidirectional barbed sutures for wound closure: evolution and applications. J Am Col Certif Wound Spec 2009; 1: 51–57.
6. Ruff G. Techniques and uses for absorbable barbed sutures. Aesthet Surg J 2006; 26: 620–628.
7. Hammond DC. Barbed sutures in plastic surgery: a personal experience. Aesthet Surg J 2013; 33: 32S–39S.
8. Ruff GL. The history of barbed sutures. Aesthet Surg J 2013; 33: 12S–16S.
9. Matarasso A. Introduction to the barbed sutures supplement: the expanding applications of barbed sutures. Aesthet Surg J 2013; 33 (suppl 3):7S–11S.
10. Murtha AP, Kaplan AL, Paglia MJ, et al. Evaluation of a novel technique for wound closure using a barbed suture. Plast Reconstr Surg 2006; 117: 1769–1780.
11. Villa MT, White LE, Alam M, et al. Barbed sutures: a review of the literature. Plast Reconstr Surg 2008; 121: 102e–108e.
12. Hurwitz DJ, Reuben B. Quill barbed sutures in body contouring surgery: a 6-year comparison with running absorbable braided sutures. Aesthet Surg J 2013; 33: 44S–56S.
13. Nett M, Avelar R, Sheehan M, et al. Water-tight knee arthrotomy closure: comparison of a novel single bidirectional barbed self-retaining running suture versus conventional interrupted sutures. J Knee Surg 2011; 24: 55–59.
14. Moya AP. Barbed sutures in body surgery. Aesthet Surg J 2013; 33: 57S–71S.
15. Pham KN, Sack BS, O'Connor RC, et al. V-Loc urethrointestinal anastomosis during robotic cystectomy with orthotopic urinary diversion. Can Urol Assoc J 2013; 7: E663–E666.
16. Sato M, Matsumura H, Gondo M, et al. Flexor tendon repair with barbed suture: an experimental study. Eur J Orthop Surg Traumatol 2014; 24: 1421–1424.
17. Lin TE, Lakhiani C, Lee MR, et al. Biomechanical analysis of knotless flexor tendon repair using large-diameter unidirection barbed suture. Hand (N Y) 2013; 8: 315–319.
18. Iavazzo C, Mamais I, Gkegkes ID. The role of knotless barbed suture in gynecologic surgery: systematic review and meta-analysis. Surg Innov 2015; 22: 528–539.
19. Greenberg JA, Goldman RH. Barbed suture: a review of the technology and clinical uses in obstetrics and gynecology. Rev Obstet Gynecol 2013; 6: 107–115.
20. Spah CE, Elkins AD, Wehrenberg A, et al. Evaluation of two novel self-anchoring barbed sutures in a prophylactic laparoscopic gastropexy compared with intracorporeal tied knots. Vet Surg 2013; 42: 932–942.
21. Miller J, Zaruby J, Kaminskaya K. Evaluation of a barbed suture device versus conventional suture in a canine enterotomy model. J Invest Surg 2012; 25: 107–111.
22. Ehrhart NP, Kaminskaya K, Miller JA, et al. In vivo assessment of absorbable knotless barbed suture for single layer gastrotomy and enterotomy closure. Vet Surg 2013; 42: 210–216.
23. Nelson BB, Hassel DM. In vitro comparison of V-Loc versus Biosyn in a one-layer end-to-end anastomosis of equine jejunum. Vet Surg 2014; 43: 80–84.
24. Templeton MM, Krebs AI, Kraus KH, et al. Ex vivo biomechanical comparison of V-Loc 180 absorbable wound closure device and standard polyglyconate suture for diaphragmatic herniorrhaphy in a canine model. Vet Surg 2015; 44: 65–69.
25. Alvarez WA, Scharf VF, Case JB. Comparison of laparoscopic and open cystopexy in a cadaveric canine model. Vet Surg 2015; 44: 44–49.
26. Arbaugh M, Case JB, Monnet E. Biomechanical comparison of glycomer 631 and glycomer 631 knotless for use in canine incisional gastropexy. Vet Surg 2013; 42: 205–209.
27. Ragle CA, Yiannikouris S, Tibary AA, et al. Use of a barbed suture for laparoscopic closure of the internal inguinal rings in a horse. J Am Vet Med Assoc 2013; 242: 249–253.
28. Imhoff DJ, Cohen A, Monnet E. Biomechanical analysis of laparoscopic incisional gastropexy with intracorporeal suturing using knotless polyglyconate. Vet Surg 2015; 44: 39–43.
29. Greenberg JA, Walden S, Hammer CM, et al. A comparison of barbed and smooth suture for ovine cesarean delivery. Int J Gynaecol Obstet 2011; 113: 215–217.
30. Kadimcherla P, Lovy AJ, Sambaziotis C, et al. Knee arthrotomy closure with barbed suture in flexion versus extension: a porcine study. J Arthroplasty 2014; 29: 2211–2213.
31. Jordan MC, Hölscher-Doht S, Jakubietz MG, et al. Suture material for flexor tendon repair: 3–0 V-Loc versus 3–0 Stratafix in a biomechanical comparison ex vivo. J Orthop Surg Res 2014; 9: 72.
32. Zaruby J, Gingras K, Taylor J, et al. An in vivo comparison of barbed suture devices and conventional monofilament sutures for cosmetic skin closure: biomechanical wound strength and histology. Aesthet Surg J 2011; 31: 232–240.
33. Fong ED, Bartlett AS, Malak S, et al. Tensile strength of surgical knots in abdominal wound closure. ANZ J Surg 2008; 78: 164–166.
34. Paul MD. Using barbed sutures in open/subperiosteal mid-face lifting. Aesthet Surg J 2006; 26: 725–732.
35. Zhao C, Hsu C, Moriya T, et al. Beyond the square knot: a novel knotting technique for surgical use. J Bone Joint Surg Am 2013; 95: 1020–1027.
36. Helling ER, Okpaku A, Wang PTH, et al. Complications of facial suspension sutures. Aesthet Surg J 2007; 27: 155–161.
37. Sulamanidze M, Sulamanidze G. APTOS suture lifting methods: 10 years of experience. Clin Plast Surg 2009; 36: 281–306.
38. Gingras K, Zaruby J, Maul D. Comparison of V–Loc 180 wound closure device and Quill PDO knotless tissue-closure device for intradermal closure in a porcine in vivo model: evaluation of biomechanical wound strength. J Biomed Mater Res B Appl Biomater 2012; 100B:1053–1058.
39. van Rijssel EJC, Brand R, Admiraal C, et al. Tissue reaction and surgical knots: the effect of suture size, knot configuration, and knot volume. Obstet Gynecol 1989; 74: 64–68.
40. Ingle NP, King MW. Optimizing the tissue anchoring performance of barbed sutures in skin and tendon tissues. J Biomech 2010; 43: 302–309.
41. Smeak DD. Buried continuous intradermal suture closure. Compend Contin Educ Pract Vet 1992; 14: 907–919.
42. Covidien. V-Loc 90 and V-Loc 180 absorbable wound closure devices step-by-step guide to dermal wound closure applications. Available at: www.medtronic.com/content/dam/covidien/library/us/en/product/wound-closure/v-loc-wound-closure-devices-guide-to-wound-closure-applications.pdf. Accessed Oct 11 26, 2016.
43. Regier PJ, Smeak DD, Coleman K, et al. Comparison of volume, security, and biomechanical strength of square and Aberdeen termination knots tied with 4-0 polyglyconate and used for termination of intradermal closures in canine cadavers. J Am Vet Med Assoc 2015; 247: 260–266.
